<!DOCTYPE html>
<html lang="zh-CN">
    <head>
        <meta charset="UTF-8" />
        <title>22_定位-特殊情况1-z-index定位层级-父子关系</title>
        <style>

            /* 父子关系不涉及到层级 */
            #outer {
                position: absolute;
                z-index: 0;
                width: 300px;
                height: 300px;
                background-color: aqua;
            }

            #inner {
                position: absolute;
                z-index: 3;
                width: 100px;
                height: 100px;
                background-color: red;
            }
        </style>
    </head>
    <body>
        <div id="outer">
            <div id="inner">

            </div>
        </div>
    </body>
</html>